On Sunday, July 1, the International Space Station temporarily lost command and voice link with Houston, the primary ISS mission control center. The issue was resolved within a few hours during which time Houston was unable to communicate with ISS.
The problem occurred when the Flight Control Room in Houston suffered a primary and backup failure of its Front-End Processor. It is hypothesized that the failure was related to Sunday’s leap second and the programming updates pertaining thereto. Following the contingency protocol, Mission Control personnel moved to the Training or “Red” Flight Control Room for the duration of the failure after immediate troubleshooting efforts proved unsuccessful. They were able to return early Monday.
Although the three crewmembers aboard the station were in a scheduled sleep cycle, Commander Padalka did attempt to call Houston during the issue. When unable to get through, he followed procedure and called Moscow Mission Control. Had he been unable to reach Moscow, the next contigency called for a switch to the ISS IP phone, orchestrated via netmeeting between Houston and NASA Flight Engineer Joe Acaba. The IP phone is commonly used on the station for more private family communications.
Due to the issue, an altitude adjustment was delayed by three orbits. The adjustment was planned in advance, taking the station back to its nominal orbit after the Soyuz TMA-03M undocking and the delay had no negative impact. The communications system is one station component that is scheduled for an update in the near future, although the planned increase in bandwidth likely would have no effect on Sunday’s issue.
The ISS crew is currently awaiting the other half of its complement. The remainder of Expedition 32 – JAXA’s Akihiko Hoshide, NASA’s Sunita Williams, and Roscosmos’ Yuri Malenchenko – are currently in Baikonur preparing for a July 14 launch.
Below, The ISS Update for July 2, which makes no mention of the communication issue: